1. Field of the Invention
The invention relates to a method for influencing and monitoring the oxide layer on metallic components of hot CO2/H2O cycle systems, in particular of CO2/H2O gas turbines.
2. Brief Description of the Related Art
CO2/H2O gas turbine systems having a largely closed CO2 gas turbine cycle are known. A gas turbine system of this type comprises at least one compressor, at least one combustion chamber, at least one turbine, at least one heat sink and a water separator. In the combustion chamber, the fuel (hydrocarbon, e.g. natural gas with methane CH4 as its main component) reacts with the oxygen of the atmosphere prepared from O2, CO2 and if appropriate H2O.
The components CO2 and H2O formed as a result of the combustion, as well as any inert gases introduced with the oxygen or the natural gas, are removed on an ongoing basis, so that a cycle with a substantially constant composition of the working medium is maintained.
Unlike in conventional gas turbine systems, in which the exhaust gases still contain a high level of O2, the working medium in a cycle process of this type, predominantly comprising CO2 and H2O, may have reducing properties. Consequently, at the high temperatures which usually prevail in the combustion chamber and in the turbine, the protective oxide layer on the metal surfaces of the components that are subject to thermal load may disadvantageously be worn away. These components are then corroded quickly and can lead to undesirable premature failure.